I damaged the wire going into my rear hub, can I fix it by myself or not?

[User1832839]

I was riding my bike and I skidded. The wire going into my rear hub had the outer insulation scraped off very close to the point where it goes into the hub. The wires inside had there insulation scraped off as well but they are not crushed/touching and the copper (which is now open) has no visible damage.
My problem started when I didn't notice it and took it out again, when it was put under any amount of load/weight the wire had small sparks coming out and the bike would cut out. I immediately stopped using it and took it to a repair service where they charged me 100 pounds for fixing the wire (despite leaving it open), after this I started to use it gain and halfway through a ride it lost power and cut out again. I assumed it was just low on battery so I charged the battery and tried to turn it on again.
It turned on and I lifted the wheel up (so there was no load/torque of the wheel) and it worked fine and reached it top speed easily however as soon as the wheel touched the floor the power cut out.

I then left it for a couple days and when I checked back up on it it would not turn on at all unless the wire was held in a specific position, so I then assumed it was because the wire was open because it could circulate small amounts of current but when the torque was increased it could pass enough current through to turn the wheel and it shorted out on itself.
I want to know if I am right or not, if I'm wrong please tell me what is happening and if I can fix this myself easily or I need to get a professional to fix it.
I am a 67 year old man and I do not want to spend another large amount of money of the bike without knowing that It's the best option to do so.
I have included as much detail as I can so please help me, anything is appreciated.
Thank you

 

[procreator]

Can you post a picture?

My first thought is that you need to be familiar with working with low voltage wires.

However, from the sounds of it the repair could be difficult. If one of the wires is broken inside the hub "tunnel" that guides the wires into the motor, then you may not be able to fix it at all unless that part can be removed from the hub. If it can't you may need to replace the motor, or find a complete wheel that matches the wiring of the existing one.

 

[Freddy1]

I immediately stopped using it and took it to a repair service where they charged me 100 pounds for fixing the wire (despite leaving it open), after this I started to use it gain and halfway through a ride it lost power and cut out again.

When you say "despite leaving it open" I was initially a bit confused what you meant. Going back and rereading your comment, am I right in thinking this is still the exposed copper inner core? This is how you've used the term.

If that is so, that isn't anything like a professional repair, and for a 100 pound repair bill I would be concerned you've encountered some dodgy outfit. However, they are obligated by law to do a proper professional repair, so take it back and politely don't take "no" for an answer. Tell them you want it fixed, correctly this time, at no additional charge.

Only after you've exhausted the above without result consider going to 'plan B'.

 

[Mustangmike]

There are 9 wires in the cable going through the axle into the hub motor. To fix this right you a new harness soldered into place onto the board inside the motor

 

[ElHegpah]

Generally, only eight wires. Three (thick) phase, three (very thin) Halls plus two for Halls power. Ninth wire on some bikes likely a temp or speed sensor. A few motors have only the three phase wires. Sensorless.

Wires run thru the axle, soldered inside the motor. PITA to fish the wires thru the axle. If you do this yourself, seek out the "CLANG!" video. Depending on motor rating, strong to extremely powerful magnetic pull on motor side cover when replacing. Fingertips in real danger.